Study of High Sensitivity Total-Internal-Reflection Atmosphere Pressure Sensor

• Main Authors: Chiang,Keng-Huan, 蔣庚寰
• Other Authors: Lin,Jiun-You
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/39b573

碩士 === 國立彰化師範大學 === 機電工程學系 === 106 === In this thesis, a method for measuring the air pressure is proposed using highly sensitive total reflection heterodyne interferometry. After passing through a phase shifter formed by some wave plates, a heterodyne light beam penetrates into an isosceles prism with the bottom in contact with an air pressure cavity, and it is totally reflected; then, the totally reflected light beam travels an analyzer for interference. When the fast axis and the transmission axis of the wave plates and the analyzer are set at specific azimuth angles, the phase difference associated with the air pressure of the interference signal is greatly increased. Therefore, the change of the air pressure in the cavity results in a significant the phase difference variation of the interference signal. The variation can easily be measured with heterodyne interferometry, and the pressure change is obtainable from the measured phase difference. The feasibility was demonstrated by experimental results. The sensitivity and the resolution of this method are up to 0.12 degree/torr and 0.25 torr, respectively in a range from 10 to 2090 torr. Due to being the common-path heterodyne interferometry, the method provides the advantages of instant response, excellent resistance to light source instability, adjustable sensitivity, and high sensitivity and accuracy.